The unsolved murder of a student at the Texas Medical Center has prompted Crime Stoppers of Houston to offer a $200,000 reward, the largest cash amount ever in the organization's history.

Crime Stoppers announced last month an increased reward of $10,000 for information leading to an arrest or charges in the Jan. 16 fatal shooting of Gelareh Bagherzadeh, an outspoken critic of human rights policies in her native Iran.

On Tuesday, the organization increased that amount yet again, to $200,000. Houston Police Department Sgt. J.C. Padilla said investigators have no motive in the case.

"We are not ruling out anything at this point," Padilla said. "The more we talk to people, the more we realize we need the community's help."

Katherine Cabaniss, executive director of Crime Stoppers of Houston, said the reward doubles the previous largest reward of $100,000 offered in the 2006 Clear Lake murders of four young people. It resulted in a tip that helped solve the case, she said.

"Rewards of this size work," Cabaniss said.

Bagherzadeh, 30, was shot while driving her car about 12:30 a.m. outside her parents' townhome in the 800 block of Augusta near Sugar Hill near the Galleria area. After she was shot, the vehicle crashed into property in the townhouse complex.

Nothing was taken from the vehicle, but Houston police haven't ruled out the possibility it could have been a botched robbery. Investigators in January also had not found any evidence suggesting she was targeted for her nationality or activism.

Anyone with information about suspects is asked to contact Crime Stoppers of Houston at 713-222-TIPS (8477).

Tips also can be submitted online at www.crime-stoppers.org or sent by text message. Text TIP610 plus your tip to CRIMES (274637). All tipsters remain anonymous.

Robert Stanton is a breaking news reporter at the Houston Chronicle. A veteran journalist with 30 years in the news business, he began his career in 1982 at The Galveston Daily News, and in 1987 joined The Houston Post as a general assignment reporter, covering police, criminal courts and minority affairs. He also has worked on the assignments desk at KHOU-11 News, was news editor at The Houston Defender, and has written freelance articles for publications that include Agence France-Presse, Minority Business News, BETWeekend, Inside Houston and The Houston Press. He lives in Galveston, where he is a proud BOI (Born On the Island) resident.